Structural member formed from a solid lineal profile

ABSTRACT

A structural member that contains a solid lineal profile that is formed from a plurality of consolidated ribbons is provided. Each of the ribbons includes unidirectionally aligned continuous fibers embedded within a thermoplastic polymer matrix. The continuous fiber ribbons are laminated together during pultrusion to form an integral solid profile having very high tensile strength properties. Contrary to conventional wisdom, the present inventors have discovered that careful control over certain aspects of the pultrusion process can allow such high strength profiles to be readily formed without adversely impacting the pultrusion apparatus.

The present application claims priority as a divisional application ofU.S. Ser. No. 13/698,389, filed Nov. 16, 2012, which is a U.S. NationalStage filing of International Patent Application No. PCT/US2011/039953filed Jun. 10, 2011, which claims priority to Provisional ApplicationSer. No. 61/353,885, filed Jun. 11, 2010, the entire contents of whichare incorporated herein by reference thereto.

BACKGROUND OF THE INVENTION

Solid profiles are often formed by pultruding one or morefiber-reinforced ribbons through a die that shapes the ribbons into thedesired configuration. The ribbons may include unidirectionally alignedcontinuous fibers embedded within a polymer matrix. Because the profileshave continuous fibers oriented in the machine direction (longitudinal),they often exhibit good tensile strength in the machine direction.Unfortunately, however, the maximum degree of tensile strength that isachievable is often limited due to the difficulty in processingmaterials of a very high degree of strength. As such, a need currentlyexists for a solid profile that exhibits excellent tensile strength, andyet can be made in a relatively efficient and simple manner.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a structuralmember is disclosed that comprises a solid lineal profile. The solidlineal profile contains a first component formed from a consolidatedlaminate of ribbons, wherein each ribbon of the laminate contains aplurality of continuous fibers that are substantially oriented in alongitudinal direction and a resinous matrix that contains one or morethermoplastic polymers and within which the continuous fibers areembedded. The continuous fibers constitute from about 40 wt. % to about90 wt. % of the ribbon and the thermoplastic polymers constitute fromabout 10 wt. % to about 60 wt. % of the ribbon. The flexural modulus isabout 10 Gigapascals or more.

In accordance with another embodiment of the present invention, a methodfor forming a solid lineal profile is disclosed that comprises supplyinga plurality of individual ribbons. Each ribbon contains a plurality ofcontinuous fibers that are substantially oriented in a longitudinaldirection and a resinous matrix that contains one or more thermoplasticpolymers and within which the continuous fibers are embedded, thecontinuous fibers constituting from about 40 wt. % to about 90 wt. % ofthe ribbon and the thermoplastic polymers constituting from about 10 wt.% to about 60 wt. % of the ribbon. The ribbons are heated to atemperature at or above the softening temperature of the resinousmatrix. The heated ribbons are pulled through a first die to consolidatethe ribbons together and form a laminate and through a second die toshape the laminate. The shaped laminate is cooled to form the solidprofile.

Other features and aspects of the present invention are set forth ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures, in which:

FIG. 1 is a schematic illustration of one embodiment of an impregnationsystem for use in the present invention;

FIG. 2A is a cross-sectional view of the impregnation die shown in FIG.1;

FIG. 2B is an exploded view of one embodiment of a manifold assembly andgate passage for an impregnation die that may be employed in the presentinvention;

FIG. 2C is a perspective view of one embodiment of a plate at leastpartially defining an impregnation zone that may be employed in thepresent invention;

FIG. 3 is a schematic illustration of one embodiment of a pultrusionsystem that may be employed in the present invention;

FIG. 4 is a perspective view of one embodiment of a pultrusion die thatmay be employed in the system of FIG. 3;

FIG. 5 is a cross-sectional view of one embodiment of the solid profileof the present invention;

FIG. 6 is a cross-sectional view of another embodiment of the solidprofile of the present invention; and

FIG. 7 is a cross-sectional view of yet another embodiment of the solidprofile of the present invention.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS Definitions

As used herein, the term “profile” generally refers to a pultruded part.The profile may possess a wide variety of cross-sectional shapes, suchas square, rectangular, circular, elliptical, triangular, I-shaped,C-shaped, U-shaped, J-shaped, L-shaped, etc.

As used herein, the term “lineal” generally refers to a cross-sectionalshape that is substantially the same along the entire length of theprofile.

As used herein, the term “continuous fibers” generally refers to fibers,filaments, yarns, or rovings (e.g., bundles of fibers) having a lengthgreater than about 8 millimeters, in some embodiments about 15millimeters or more, and in some embodiments, about 20 millimeters ormore.

As used herein, the term “discontinuous fibers” generally refers tofibers, filaments, yarns, or rovings that are not continuous. Suchfibers typically have a length of about 8 millimeters or less. Forexample, discontinuous fibers may include short or long fibers. “Longfibers” are typically those fibers having a length of from about 0.5 toabout 8 millimeters, in some embodiments, from about 0.8 to about 6millimeters, and in some embodiments, from about 1 to about 5millimeters. “Short fibers” are typically those fibers having a lengthof about 0.5 millimeter or less, in some embodiments about 0.01 to about0.4 millimeters, and in some embodiments, from about 0.05 to about 0.3millimeters.

Detailed Description

It is to be understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention.

Generally speaking, the present invention is directed to a structuralmember for use in various applications, such as windows, doors, sidingpanels, decking, flooring, etc. The structural member contains a solidlineal profile that is formed from a plurality of consolidated ribbons,each of which includes unidirectionally aligned continuous fibersembedded within a thermoplastic polymer matrix. The continuous fiberribbons are laminated together during pultrusion to form an integralsolid profile having very high tensile strength properties. Contrary toconventional wisdom, the present inventors have discovered that carefulcontrol over certain aspects of the pultrusion process can allow suchhigh strength profiles to be readily formed without adversely impactingthe pultrusion apparatus. Various embodiments of the present inventionwill now be described in more detail.

The continuous fibers employed in the present invention may be formedfrom any conventional material known in the art, such as metal fibers;glass fibers (e.g., E-glass, A-glass, C-glass, D-glass, AR-glass,R-glass, S1-glass, S2-glass), carbon fibers (e.g., graphite), boronfibers, ceramic fibers (e.g., alumina or silica), aramid fibers (e.g.,Kevlar® marketed by E. I. duPont de Nemours, Wilmington, Del.),synthetic organic fibers (e.g., polyamide, polyethylene, paraphenylene,terephthalamide, polyethylene terephthalate and polyphenylene sulfide),and various other natural or synthetic inorganic or organic fibrousmaterials known for reinforcing thermoplastic compositions. Glass fibersand carbon fibers are particularly desirable for use in the continuousfibers. Such fibers often have a nominal diameter of about 4 to about 35micrometers, and in some embodiments, from about 9 to about 35micrometers. The fibers may be twisted or straight. If desired, thefibers may be in the form of rovings (e.g., bundle of fibers) thatcontain a single fiber type or different types of fibers. Differentfibers may be contained in individual rovings or, alternatively, eachroving may contain a different fiber type. For example, in oneembodiment, certain rovings may contain continuous carbon fibers, whileother rovings may contain glass fibers. The number of fibers containedin each roving can be constant or vary from roving to roving. Typically,a roving may contain from about 1,000 fibers to about 50,000 individualfibers, and in some embodiments, from about 2,000 to about 40,000fibers.

Any of a variety of thermoplastic polymers may be employed to form thethermoplastic matrix in which the continuous are embedded. Suitablethermoplastic polymers for use in the present invention may include, forinstance, polyolefins (e.g., polypropylene, propylene-ethylenecopolymers, etc.), polyesters (e.g., polybutylene terephalate (“PBT”)),polycarbonates, polyamides (e.g., Nylon™), polyether ketones (e.g.,polyetherether ketone (“PEEK”)), polyetherimides, polyarylene ketones(e.g., polyphenylene diketone (“PPDK”)), liquid crystal polymers,polyarylene sulfides (e.g., polyphenylene sulfide (“PPS”)),fluoropolymers (e.g., polytetrafluoroethylene-perfluoromethylvinyletherpolymer, perfluoro-alkoxyalkane polymer, petrafluoroethylene polymer,ethylene-tetrafluoroethylene polymer, etc.), polyacetals, polyurethanes,polycarbonates, styrenic polymers (e.g., acrylonitrile butadiene styrene(“ABS”)), and so forth. Polybutylene terephalate (“PBT”) is aparticularly suitable thermoplastic polymer.

The continuous fiber ribbons of the present invention are generallyformed using an extrusion device within which the continuous fibers areembedded with the thermoplastic matrix. Among other things, theextrusion device facilitates the ability of the thermoplastic polymer tobe applied to the entire surface of the fibers. The resulting ribbonalso has a very low void fraction, which helps enhance the strength ofthe ribbon. For instance, the void fraction may be about 3% or less, insome embodiments about 2% or less, and in some embodiments, about 1% orless. The void fraction may be measured using techniques well known tothose skilled in the art. For example, the void fraction may be measuredusing a “resin burn off” test in which samples are placed in an oven(e.g., at 600° C. for 3 hours) to burn out the resin. The mass of theremaining fibers may then be measured to calculate the weight and volumefractions. Such “burn off” testing may be performed in accordance withASTM D 2584-08 to determine the weights of the fibers and thethermoplastic matrix, which may then be used to calculate the “voidfraction” based on the following equations:V _(f)=100*(ρ_(t)−ρ_(c))/ρ_(t)where,

-   -   V_(f) is the void fraction as a percentage;    -   ρ_(c) is the density of the composite as measured using known        techniques, such as with a liquid or gas pycnometer (e.g.,        helium pycnometer);    -   ρ_(t) is the theoretical density of the composite as is        determined by the following equation:        ρ_(t)=1/[W _(f)/ρ_(f) +W _(m)/ρ_(m)]    -   ρ_(m) is the density of the thermoplastic matrix (e.g., at the        appropriate crystallinity);    -   ρ_(f) is the density of the fibers;    -   W_(f) is the weight fraction of the fibers; and    -   W_(m) is the weight fraction of the thermoplastic matrix.

Alternatively, the void fraction may be determined by chemicallydissolving the resin in accordance with ASTM D 3171-09. The “burn off”and “dissolution” methods are particularly suitable for glass fibers,which are generally resistant to melting and chemical dissolution. Inother cases, however, the void fraction may be indirectly calculatedbased on the densities of the thermoplastic polymer, fibers, and ribbonin accordance with ASTM D 2734-09 (Method A), where the densities may bedetermined ASTM D792-08 Method A. Of course, the void fraction can alsobe estimated using conventional microscopy equipment.

Referring to FIG. 1, for example, one embodiment of an extrusion deviceis shown that may be employed to impregnate the fibers with athermoplastic polymer. More particularly, the apparatus includes anextruder 120 containing a screw shaft 124 mounted inside a barrel 122. Aheater 130 (e.g., electrical resistance heater) is mounted outside thebarrel 122. During use, a thermoplastic polymer feedstock 127 issupplied to the extruder 120 through a hopper 126. The thermoplasticfeedstock 127 is conveyed inside the barrel 122 by the screw shaft 124and heated by frictional forces inside the barrel 122 and by the heater130. Upon being heated, the feedstock 127 exits the barrel 122 through abarrel flange 128 and enters a die flange 132 of an impregnation die150.

A continuous fiber roving 142 or a plurality of continuous fiber rovings142 are supplied from a reel or reels 144 to die 150. The rovings 142are generally kept apart a certain distance before impregnation, such asat least about 4 millimeters, and in some embodiments, at least about 5millimeters. The feedstock 127 may further be heated inside the die byheaters 133 mounted in or around the die 150. The die is generallyoperated at temperatures that are sufficient to cause melting andimpregnation of the thermoplastic polymer. Typically, the operationtemperatures of the die is higher than the melt temperature of thethermoplastic polymer, such as at temperatures from about 200° C. toabout 450° C. When processed in this manner, the continuous fiberrovings 142 become embedded in the polymer matrix, which may be a resin214 (FIG. 2A) processed from the feedstock 127. The mixture is thenextruded from the impregnation die 150 to create an extrudate 152.

A pressure sensor 137 (FIG. 2A) senses the pressure near theimpregnation die 150 to allow control to be exerted over the rate ofextrusion by controlling the rotational speed of the screw shaft 124, orthe federate of the feeder. That is, the pressure sensor 137 ispositioned near the impregnation die 150 so that the extruder 120 can beoperated to deliver a correct amount of resin 214 for interaction withthe fiber rovings 142. After leaving the impregnation die 150, theextrudate 152, or impregnated fiber rovings 142, may enter an optionalpre-shaping, or guiding section (not shown) before entering a nip formedbetween two adjacent rollers 190. Although optional, the rollers 190 canhelp to consolidate the extrudate 152 into the form of a ribbon (ortape), as well as enhance fiber impregnation and squeeze out any excessvoids. In addition to the rollers 190, other shaping devices may also beemployed, such as a die system. The resulting consolidated ribbon 156 ispulled by tracks 162 and 164 mounted on rollers. The tracks 162 and 164also pull the extrudate 152 from the impregnation die 150 and throughthe rollers 190. If desired, the consolidated ribbon 156 may be wound upat a section 171. Generally speaking, the ribbons are relatively thinand typically have a thickness of from about 0.05 to about 1 millimeter,in some embodiments from about 0.1 to about 0.8 millimeters, and in someembodiments, from about 0.2 to about 0.4 millimeters.

Within the impregnation die, it is generally desired that the rovings142 are traversed through an impregnation zone 250 to impregnate therovings with the polymer resin 214. In the impregnation zone 250, thepolymer resin may be forced generally transversely through the rovingsby shear and pressure created in the impregnation zone 250, whichsignificantly enhances the degree of impregnation. This is particularlyuseful when forming a composite from ribbons of a high fiber content,such as about 35% weight fraction (“Wf”) or more, and in someembodiments, from about 40% Wf or more. Typically, the die 150 willinclude a plurality of contact surfaces 252, such as for example atleast 2, at least 3, from 4 to 7, from 2 to 20, from 2 to 30, from 2 to40, from 2 to 50, or more contact surfaces 252, to create a sufficientdegree of penetration and pressure on the rovings 142. Although theirparticular form may vary, the contact surfaces 252 typically possess acurvilinear surface, such as a curved lobe, rod, etc. The contactsurfaces 252 are also typically made of a metal material.

FIG. 2A shows a cross-sectional view of an impregnation die 150. Asshown, the impregnation die 150 includes a manifold assembly 220, a gatepassage 270, and an impregnation zone 250. The manifold assembly 220 isprovided for flowing the polymer resin 214 therethrough. For example,the manifold assembly 220 may include a channel 222 or a plurality ofchannels 222. The resin 214 provided to the impregnation die 150 mayflow through the channels 222.

As shown in FIG. 2B, some portions of the channels 222 may becurvilinear, and in exemplary embodiments, the channels 222 have asymmetrical orientation along a central axis 224. Further, in someembodiments, the channels may be a plurality of branched runners 222,which may include first branched runner group 232, second group 234,third group 236, and, if desired, more branched runner groups. Eachgroup may include 2, 3, 4 or more runners 222 branching off from runners222 in the preceding group, or from an initial channel 222.

The branched runners 222 and the symmetrical orientation thereofgenerally evenly distribute the resin 214, such that the flow of resin214 exiting the manifold assembly 220 and coating the rovings 142 issubstantially uniformly distributed on the rovings 142. This desirablyallows for generally uniform impregnation of the rovings 142.

Further, the manifold assembly 220 may in some embodiments define anoutlet region 242, which generally encompasses at least a downstreamportion of the channels or runners 222 from which the resin 214 exits.In some embodiments, at least a portion of the channels or runners 222disposed in the outlet region 242 have an increasing area in a flowdirection 244 of the resin 214. The increasing area allows for diffusionand further distribution of the resin 214 as the resin 214 flows throughthe manifold assembly 220, which further allows for substantiallyuniform distribution of the resin 214 on the rovings 142.

As further illustrated in FIGS. 2A and 2B, after flowing through themanifold assembly 220, the resin 214 may flow through gate passage 270.Gate passage 270 is positioned between the manifold assembly 220 and theimpregnation zone 250, and is provided for flowing the resin 214 fromthe manifold assembly 220 such that the resin 214 coats the rovings 142.Thus, resin 214 exiting the manifold assembly 220, such as throughoutlet region 242, may enter gate passage 270 and flow therethrough, asshown.

Upon exiting the manifold assembly 220 and the gate passage 270 of thedie 150 as shown in FIG. 2A, the resin 214 contacts the rovings 142being traversed through the die 150. As discussed above, the resin 214may substantially uniformly coat the rovings 142, due to distribution ofthe resin 214 in the manifold assembly 220 and the gate passage 270.Further, in some embodiments, the resin 214 may impinge on an uppersurface of each of the rovings 142, or on a lower surface of each of therovings 142, or on both an upper and lower surface of each of therovings 142. Initial impingement on the rovings 142 provides for furtherimpregnation of the rovings 142 with the resin 214.

As shown in FIG. 2A, the coated rovings 142 are traversed in rundirection 282 through impregnation zone 250, which is configured toimpregnate the rovings 142 with the resin 214. For example, as shown inFIGS. 2A and 2C, the rovings 142 are traversed over contact surfaces 252in the impregnation zone. Impingement of the rovings 142 on the contactsurface 252 creates shear and pressure sufficient to impregnate therovings 142 with the resin 214 coating the rovings 142.

In some embodiments, as shown in FIG. 2A, the impregnation zone 250 isdefined between two spaced apart opposing plates 256 and 258. Firstplate 256 defines a first inner surface 257, while second plate 258defines a second inner surface 259. The contact surfaces 252 may bedefined on or extend from both the first and second inner surfaces 257and 259, or only one of the first and second inner surfaces 257 and 259.FIG. 2C illustrates the second plate 258 and the various contactsurfaces thereon that form at least a portion of the impregnation zone250 according to these embodiments. In exemplary embodiments, as shownin FIG. 2A, the contact surfaces 252 may be defined alternately on thefirst and second surfaces 257 and 259 such that the rovings alternatelyimpinge on contact surfaces 252 on the first and second surfaces 257 and259. Thus, the rovings 142 may pass contact surfaces 252 in a waveform,tortuous or sinusoidual-type pathway, which enhances shear.

The angle 254 at which the rovings 142 traverse the contact surfaces 252may be generally high enough to enhance shear, but not so high to causeexcessive forces that will break the fibers. Thus, for example, theangle 254 may be in the range between approximately 1° and approximately30°, and in some embodiments, between approximately 5° and approximately25°.

In alternative embodiments, the impregnation zone 250 may include aplurality of pins (not shown), each pin having a contact surface 252.The pins may be static, freely rotational, or rotationally driven. Infurther alternative embodiments, the contact surfaces 252 andimpregnation zone 250 may comprise any suitable shapes and/or structuresfor impregnating the rovings 142 with the resin 214 as desired orrequired.

To further facilitate impregnation of the rovings 142, they may also bekept under tension while present within the impregnation die. Thetension may, for example, range from about 5 to about 300 Newtons, insome embodiments from about 50 to about 250 Newtons, and in someembodiments, from about 100 to about 200 Newtons per roving 142 or towof fibers.

As shown in FIG. 2A, in some embodiments, a land zone 280 may bepositioned downstream of the impregnation zone 250 in run direction 282of the rovings 142. The rovings 142 may traverse through the land zone280 before exiting the die 150. As further shown in FIG. 2A, in someembodiments, a faceplate 290 may adjoin the impregnation zone 250.Faceplate 290 is generally configured to meter excess resin 214 from therovings 142. Thus, apertures in the faceplate 290, through which therovings 142 traverse, may be sized such that when the rovings 142 aretraversed therethrough, the size of the apertures causes excess resin214 to be removed from the rovings 142.

The impregnation die shown and described above is but one of variouspossible configurations that may be employed in the present invention.In alternative embodiments, for example, the fibers may be introducedinto a crosshead die that is positioned at an angle relative to thedirection of flow of the polymer melt. As the fibers move through thecrosshead die and reach the point where the polymer exits from anextruder barrel, the polymer is forced into contact with the fibers. Itshould also be understood that any other extruder design may also beemployed, such as a twin screw extruder. Still further, other componentsmay also be optionally employed to assist in the impregnation of thefibers. For example, a “gas jet” assembly may be employed in certainembodiments to help uniformly spread a bundle or tow of individualfibers, which may each contain up to as many as 24,000 fibers, acrossthe entire width of the merged tow. This helps achieve uniformdistribution of strength properties in the ribbon. Such an assembly mayinclude a supply of compressed air or another gas that impinges in agenerally perpendicular fashion on the moving fiber tows that passacross the exit ports. The spread fiber bundles may then be introducedinto a die for impregnation, such as described above.

Regardless of the technique employed, the continuous fibers are orientedin the longitudinal direction (the machine direction “A” of the systemof FIG. 1) to enhance tensile strength. Besides fiber orientation, otheraspects of the ribbon and pultrusion process are also controlled toachieve the desired strength. For example, a relatively high percentageof continuous fibers are employed in the ribbon to provide enhancedstrength properties. For instance, continuous fibers typicallyconstitute from about 40 wt. % to about 90 wt. %, in some embodimentsfrom about 50 wt. % to about 85 wt. %, and in some embodiments, fromabout 55 wt. % to about 75 wt. % of the ribbon. Likewise, thermoplasticpolymer(s) typically constitute from about 10 wt. % to about 60 wt. %,in some embodiments from about 15 wt. % to about 50 wt. %, and in someembodiments, from about 25 wt. % to about 45 wt. % of the ribbon.

Furthermore, the profile is also formed from a combination of multiplecontinuous fibers ribbons, which are laminated together to form astrong, integrated structure having the desired thickness. The number ofribbons employed may vary based on the desired thickness and strength ofthe profile, as well as the nature of the ribbons themselves. In mostcases, however, the number of ribbons is from 5 to 40, in someembodiments from 10 to 30, and in some embodiments, from 15 to 25.

The specific manner in which the ribbons are brought together and shapedis also carefully controlled to ensure that high strength profiles canbe formed without adversely impacting the pultrusion apparatus.Referring to FIG. 3, for example, one particular embodiment of a systemand method for forming a solid profile are shown. In this embodiment, aplurality of ribbons 12 are initially provided in a wound package on acreel 20. The creel 20 may be an unreeling creel that includes a frameprovided with horizontal rotating spindles 22, each supporting apackage. A pay-out creel may also be employed, particularly if desiredto induce a twist into the fibers. It should also be understood that theribbons may also be formed in-line with the formation of the profile. Inone embodiment, for example, the extrudate 152 exiting the impregnationdie 150 from FIG. 1 may be directly supplied to the system used to forma profile. A tension-regulating device 40 may also be employed to helpcontrol the degree of tension in the ribbons 12. The device 40 mayinclude inlet plate 30 that lies in a vertical plane parallel to therotating spindles 22 of the creel 20. The tension-regulating device 40may contain cylindrical bars 41 arranged in a staggered configuration sothat the ribbons 12 passes over and under these bars to define a wavepattern. The height of the bars can be adjusted to modify the amplitudeof the wave pattern and control tension.

The ribbons 12 are heated in an oven 45 before entering theconsolidation die. Heating may be conducted using any known type ofoven, as in an infrared oven, convection oven, etc. During heating, thefibers are unidirectionally oriented to optimize the exposure to theheat and maintain even heat across the entire profile. The temperatureto which the ribbons 12 are heated is generally high enough to softenthe thermoplastic polymer to an extent that the ribbons can bondtogether. However, the temperature is not so high as to destroy theintegrity of the material. The temperature may, for example, range fromabout 80° C. to about 250° C., in some embodiments from about 90° C. toabout 200° C., and in some embodiments, from about 100° C. to about 150°C. In one particular embodiment, for example,acrylonitrile-butadiene-styrene (ABS) is used as the polymer, and theribbons are heated to or above the melting point of ABS, which is about105° C. In another embodiment, polybutylene terephalate (PBT) is used asthe polymer, and the ribbons are heated to or above the melting point ofPBT, which is about 224° C.

Upon being heated, the ribbons 12 are provided to a consolidation die 50for bonding together into a laminate 14, as well as for alignment andformation of the initial shape of the profile. As shown in FIG. 4, forexample, the ribbons 12 are guided through a channel 51 of the die 50 ina direction “A”. The channel 51 may have any of a variety of shapesand/or sizes to achieve the profile configuration. Desirably, the size(width and/or height) of the channel 51 is slightly greater than thesize of the laminate 14 to allow for expansion of the thermoplasticpolymer while heated to minimize the risk of material backup within thedie 50. For example, the width of the channel 51 may be about 2% ormore, in some embodiments about 5% or more, and in some embodiments,from about 10% to about 20% greater than the width of the laminate 14.Similarly, the height of the channel 51 may be about 2% or more, in someembodiments about 5% or more, and in some embodiments, from about 10% toabout 20% greater than the width of the laminate 14. Within the die 50,the ribbons are generally maintained at a temperature at or above themelting point of the thermoplastic matrix used in the ribbon to ensureadequate consolidation.

If desired, a second die 60 (e.g., calibration die) may also be employedthat compresses the laminate 14 into the final shape for the profile.When employed, it is generally desired that the laminate 14 is allowedto cool briefly after exiting the consolidation die 50 and beforeentering the optional second die 60. This allows the consolidatedlaminate 14 to retain its initial shape before progressing furtherthrough the system. Such cooling may be accomplished by simply exposingthe laminate 14 to the ambient atmosphere (e.g., room temperature) orthrough the use of active cooling techniques (e.g., water bath or aircooling) as is known in the art. In one embodiment, for example, air isblown onto the laminate 14 (e.g., with an air ring). The cooling betweenthese stages, however, generally occurs over a small period of time toensure that the laminate 14 is still soft enough to be further shaped.For example, after exiting the consolidation die 50, the laminate 14 maybe exposed to the ambient environment for only from about 1 to about 20seconds, and in some embodiments, from about 2 to about 10 seconds,before entering the second die 60. Within the die 60, the laminate isgenerally kept at a temperature below the melting point of thethermoplastic matrix used in the ribbon so that the shape of the profilecan be maintained.

Although referred to above as single dies, it should be understood thatthe dies 50 and 60 may in fact be formed from multiple individual dies(e.g., face plate dies).

The resulting profile may also be applied with a capping layer toenhance the aesthetic appeal of the profile and/or protect it fromenvironmental conditions. Referring again to FIG. 3, for example, such acapping layer may be applied via an extruder oriented at any desiredangle to introduce a thermoplastic resin into a capping die 72. Theresin may contain any suitable thermoplastic polymer known in the artthat is generally compatible with the thermoplastic polymer used to formthe profile. Suitable capping polymers may include, for instance,acrylic polymers, polyvinyl chloride (PVC), polybutylene terephthalate(PBT), ABS, polyolefins, polyesters, polyacetals, polyamids,polyurethanes, etc. Although the capping resin is generally free offibers, it may nevertheless contain other additives for improving thefinal properties of the profile. Additive materials employed at thisstage may include those that are not suitable for incorporating into thecontinuous fiber or long fiber layers. For instance, it may be desirableto add pigments to the composite structure to reduce finishing labor ofshaped articles, or it may be desirable to add flame retardant agents tothe composite structure to enhance the flame retarding features of theshaped article. Because many additive materials are heat sensitive, anexcessive amount of heat may cause them to decompose and producevolatile gases. Therefore, if a heat sensitive additive material isextruded with an impregnation resin under high heating conditions, theresult may be a complete degradation of the additive material. Additivematerials may include, for instance, mineral reinforcing agents,lubricants, flame retardants, blowing agents, foaming agents,ultraviolet light resistant agents, thermal stabilizers, pigments, andcombinations thereof. Suitable mineral reinforcing agents may include,for instance, calcium carbonate, silica, mica, clays, talc, calciumsilicate, graphite, calcium silicate, alumina trihydrate, bariumferrite, and combinations thereof.

While not shown in detail herein, the capping die 72 may include variousfeatures known in the art to help achieve the desired application of thecapping layer. For instance, the capping die 72 may include an entranceguide that aligns the incoming profile. The capping die may also includea heating mechanism (e.g., heated plate) that pre-heats the profilebefore application of the capping layer to help ensure adequate bonding.

Following optional capping, the shaped part 15 is then finally cooledusing a cooling system 80 as is known in the art. The cooling system 80may, for instance, be a vacuum sizer that includes one or more blocks(e.g., aluminum blocks) that completely encapsulate the profile while avacuum pulls the hot shape out against its walls as it cools. A coolingmedium may be supplied to the sizer, such as air or water, to solidifythe profile in the correct shape.

Vacuum sizers are typically employed when forming the profile. Even if avacuum sizer is not employed, however, it is generally desired to coolthe profile after it exits the capping die (or the consolidation orcalibration die if capping is not applied). Cooling may occur using anytechnique known in the art, such a vacuum water tank, cool air stream orair jet, cooling jacket, an internal cooling channel, cooling fluidcirculation channels, etc. Regardless, the temperature at which thematerial is cooled is usually controlled to achieve optimal mechanicalproperties, part dimensional tolerances, good processing, and anaesthetically pleasing composite. For instance, if the temperature ofthe cooling station is too high, the material might swell in the tooland interrupt the process. For semi-crystalline materials, too low of atemperature can likewise cause the material to cool down too rapidly andnot allow complete crystallization, thereby jeopardizing the mechanicaland chemical resistance properties of the composite. Multiple coolingdie sections with independent temperature control can be utilized toimpart the optimal balance of processing and performance attributes. Inone particular embodiment, for example, a vacuum water tank is employedthat is kept at a temperature of from about 0° C. to about 30° C., insome embodiments from about 1° C. to about 20° C., and in someembodiments, from about 2° C. to about 15° C.

As will be appreciated, the temperature of the profile as it advancesthrough any section of the system of the present invention may becontrolled to yield optimal manufacturing and desired final compositeproperties. Any or all of the assembly sections may be temperaturecontrolled utilizing electrical cartridge heaters, circulated fluidcooling, etc., or any other temperature controlling device known tothose skilled in the art.

Referring again to FIG. 3, a pulling device 82 is positioned downstreamfrom the cooling system 80 that pulls the finished profile 16 throughthe system for final sizing of the composite. The pulling device 82 maybe any device capable of pulling the profile through the process systemat a desired rate. Typical pulling devices include, for example,caterpillar pullers and reciprocating pullers. If desired, one or moresizing blocks (not shown) may also be employed. Such blocks containopenings that are cut to the exact profile shape, graduated fromoversized at first to the final profile shape. As the profile passestherethrough, any tendency for it to move or sag is counteracted, and itis pushed back (repeatedly) to its correct shape. Once sized, theprofile may be cut to the desired length at a cutting station (notshown), such as with a cut-off saw capable of performing cross-sectionalcuts.

Through control over the various parameters mentioned above, profileshaving a very high strength may be formed. For example, the profiles mayexhibit a relatively high flexural modulus. The term “flexural modulus”generally refers to the ratio of stress to strain in flexuraldeformation (units of force per area), or the tendency for a material tobend. It is determined from the slope of a stress-strain curve producedby produced by a “three point flexural” test (such as ASTM D790-10,Procedure A or ISO 178). For example, the profile of the presentinvention may exhibit a flexural modulus of from about 10 Gigapascals(“GPa) or more, in some embodiments from about 10 to about 80 GPa, insome embodiments from about 20 to about 70 GPa, and in some embodiments,from about 30 to about 60 GPa. Furthermore, the maximum flexuralstrength (also known as the modulus of rupture or bend strength) may beabout 250 Megapascals (“MPa”) or more, in some embodiments from about300 to about 1,000 MPa, and in some embodiments, from about 325 to about700 MPa. The term “maximum flexural strength” generally refers to themaximum stress reached on a stress-strain curve produced by a “threepoint flexural” test (such as ASTM D790-10, Procedure A or ISO 178) atroom temperature. It represents the ability of the material to withstandan applied stress to failure.

The profile may also has a very low void fraction, such as about 3% orless, in some embodiments about 2% or less, and in some embodiments,about 1% or less. The void fraction may be determined in the mannerdescribed above, such as using a “resin burn off” test in accordancewith ASTM D 2584-08.

One embodiment of the profile formed from the method described above isshown in more detail in FIG. 5 as element 516. As illustrated, theprofile 516 has a generally rectangular shape and is formed from acontinuous fiber component 514 formed from a plurality of laminatedribbons. A capping layer 519 also extends around the perimeter of thecontinuous fiber component 514 and defines an external surface of theprofile 516. The cross-sectional thickness (“T”) of the continuous fibercomponent 514 may be strategically selected to help achieve a particularstrength for the profile. For example, the continuous fiber component514 may have a thickness of from about 0.5 to about 40 millimeters, insome embodiments from about 1 to about 20 millimeters, and in someembodiments, from about 4 to about 10 millimeters. Likewise, thecross-sectional width (“W”) may range from about 1 to about 50millimeters, in some embodiments from about 4 to about 40 millimeters,and in some embodiments, from about 5 to about 30 millimeters. Thethickness of the capping layer 519 depends on the intended function ofthe part, but is typically from about 0.01 to about 5 millimeters, andin some embodiments, from about 0.02 to about 1.5 millimeters. The totalcross-sectional thickness or height of the profile 516 may also rangefrom about 0.5 to about 45 millimeters, in some embodiments from about 1to about 25 millimeters, and in some embodiments, from about 4 to about15 millimeters.

As will be appreciated, the particular profile embodiment describedabove is merely exemplary of the numerous designs that are made possibleby the present invention. Among the various possible profile designs, itshould be understood that additional layers of material may be employedin addition to those described above. In certain embodiments, forexample, it may be desirable to form a multi-component profile in whichone component is formed from a higher strength material and anothercomponent is formed from a lower strength material. Such multi-componentprofiles may be particularly useful in increasing overall strengthwithout requiring the need for more expensive high strength materialsfor the entire profile. The lower and/or higher strength components maybe formed from ribbon(s) that contain continuous fibers embedded withina thermoplastic matrix. Typically, the ratio of the ultimate tensilestrength (at room temperature) of the fibers used to form the highstrength material and the fibers used to form the low strength materialis from about 1.0 to about 3.0, in some embodiments from about 1.2 toabout 2.5, and in some embodiments, from about 1.4 to about 2.0. Whenemploying materials having such a strength difference, it is oftendesired that the high strength material is distributed generallysymmetrically about the cross-sectional center of the profile. Such asymmetrical distribution helps prevent buckling or other mechanicalproblems that may occur during pultrusion due to the differences inmaterial strength.

Referring to FIG. 6, for example, one embodiment of a solidmulti-component profile 600 is shown that contains a first “higherstrength” component 620 and a second “lower strength” component 640. Inthis embodiment, each component is formed from a plurality of ribbonsthat contain continuous fibers embedded within a thermoplastic polymermatrix. The continuous fibers of the lower strength component 640 may,for example, be glass fibers (e.g., E-glass) while the continuous fibersof the higher strength component may be carbon fibers. As shown in FIG.6, the higher strength component 620 is positioned so that it isadjacent to an upper surface and lower surface of the lower strengthcomponent, and thus symmetrically distributed about the cross-sectionalcenter “C” of the profile 600. Such a profile 600 may be formed usingtechniques known to those skilled in the art. For example, the upper andlower ribbons unwound from the creel 20 (FIG. 3) may be carbon fiberribbons, while the central ribbons may be glass fiber ribbons. All ofthe ribbons may thereafter be laminated and pultruded into the desiredshape as shown and described herein.

FIG. 7 shows another embodiment of a multi-component profile 700 thatcontains a higher strength component 720 and a lower strength component740. In this particular embodiment, the higher strength component (e.g.,carbon fiber ribbon) are positioned within a central area of the profile700 and distributed about a center “C.” The lower strength component 740(e.g., glass fiber ribbon) is likewise distributed about the peripheryof the higher strength component 720.

It should be understood that the present invention is by no meanslimited to the embodiments described above. For example, the profilesmay contain various other components depending on the desiredapplication. The additional components may be formed from a continuousfiber ribbon, such as described herein, as well as other types ofmaterials. In one embodiment, for example, the profile may contain alayer of discontinuous fibers (e.g., short fibers, long fibers, etc.) toimprove its transverse strength. The discontinuous fibers may beoriented so that at least a portion of the fibers are positioned at anangle relative to the direction in which the continuous fibers extend.

As indicated above, the profiles of the present invention may beemployed as a structural member for a wide variety of applications,including in windows, decking planks, railings, balusters, roofingtiles, siding, trim boards, pipes, fencing, posts, light posts, highwaysignage, roadside marker posts, etc. Windows, for example, may employone or more structural members that contain the lineal profiles of thepresent invention. For example, the window may including a frame, sash,and glazing as described in U.S. Pat. No. 6,260,251 to Guhl, which isincorporated herein in its entirety by reference thereto for allpurposes. The frame can be made of four individual frame members, whilethe sash can be made of four individual sash members. If desired, theprofiles of the present invention may be used in any component of thewindow, but may be particularly desirable for use in forming all or apart of the frame members and/or sash members.

The present disclosure may be better understood with reference to thefollowing examples.

EXAMPLE 1

Twenty one (21) continuous fiber ribbons were initially formed using anextrusion system as substantially described above and shown in FIGS.1-2. Glass fiber rovings (E-glass, 2200 tex) were employed for thecontinuous fibers with each individual ribbon containing three (3) fiberrovings. The thermoplastic polymer used to impregnate the fibers waspolybutylene terephalate, which has a melting point of about 224° C.Each ribbon contained 65.6 wt. % glass fibers and 34.4 wt. % PBS. Theresulting ribbons had a thickness of between 0.2 to 0.4 millimeters anda void fraction of less than 1%.

Once formed, the twenty one (21) ribbons were then fed to a pultrusionline operating at a speed of 15 feet per minute. Prior to consolidation,the ribbons were heated within an infrared oven (power setting of 445).The heated ribbons were then supplied to a consolidation die, such asdescribed above and shown in FIG. 3. The die contained arectangular-shaped channel that received the ribbons and consolidatedthem together while forming the initial shape of the profile. Within thedie, the ribbons remained at a temperature of about 227° C.—just abovethe melting point of the polybutylene terephalate matrix. Uponconsolidation, the resulting laminate was then briefly cooled with anair ring/tunnel device that supplied ambient air at a pressure of 8.5psi. The laminate was then passed through a nip formed between tworollers, and then to a calibration die for final shaping. Within thecalibration die, the laminate remained at a temperature of about 177° C.The resulting part was then supplied to several sizing blocks (or dies)to impart the final solid rectangular shape and cooled using a watertank at a temperature of about 7° C. The profile had a thickness of 5.87millimeters and a width of 19.94 millimeters.

To determine the strength properties of the profile, three-pointflexural testing was performed in accordance with ASTM D790-10,Procedure A. The support and nose radius was 5 millimeters, the supportspan was 3.68 inches, the specimen depth was 16×, and the test speed was0.1 inches per minute. The resulting flexural modulus was 34.6Gigapascals and the flexural strength was 546.8 Megapascals. The densityof the part was 1.917 g/cm³ and the void content was 0.51%. Further, theash content was 66.5%.

EXAMPLE 2

Eighteen (18) continuous glass fiber ribbons and (6) carbon fiberribbons were initially formed using an extrusion system as substantiallydescribed above and shown in FIGS. 1-2. Glass fiber rovings (E-glass,2200 tex) and carbon fiber rovings were employed for the continuousfibers with each individual ribbon containing three (3) fiber rovings.The thermoplastic polymer used to impregnate the fibers was polybutyleneterephalate, which has a melting point of about 224° C. Each ribboncontained 65.6 wt. % glass fibers and 34.4 wt. % PBT or 50 wt. % carbonfiber and 50 wt. % PBT. The resulting ribbons had a thickness of between0.2 to 0.4 millimeters and a void fraction of less than 1%.

Once formed, the ribbons were then fed to a pultrusion line operating ata speed of 15 feet per minute. Prior to consolidation, the ribbons wereheated within an infrared oven (power setting of 445). The heatedribbons were then supplied to a consolidation die, such as describedabove and shown in FIG. 3. The die contained a rectangular-shapedchannel that received the ribbons and consolidated them together whileforming the initial shape of the profile. Within the die, the ribbonsremained at a temperature of about 227° C., just above the melting pointof the polybutylene terephalate matrix. Upon consolidation, theresulting laminate was then briefly cooled with an air ring/tunneldevice that supplied ambient air at a pressure of 5 psi. The laminatewas then passed through a nip formed between two rollers, and then to acalibration die for final shaping. Within the calibration die, thelaminate remained at a temperature of about 177° C. The resulting partwas then supplied to several sizing blocks (or dies) to impart the finalsolid rectangular shape and cooled using a water tank at a temperatureof about 7° C. The profile had a thickness of 5.87 millimeters and awidth of 19.94 millimeters.

To determine the strength properties of the profile, three-pointflexural testing was performed in accordance with ASTM D790-10,Procedure A. The support and nose radius was 5 millimeters, the supportspan was 3.68 inches, the specimen depth was 16×, and the test speed was0.1 inches per minute. The resulting flexural modulus was 48 Gigapascalsand the flexural strength was 350 Megapascals.

These and other modifications and variations of the present inventionmay be practiced by those of ordinary skill in the art, withoutdeparting from the spirit and scope of the present invention. Inaddition, it should be understood that aspects of the variousembodiments may be interchanged both in whole or in part. Furthermore,those of ordinary skill in the art will appreciate that the foregoingdescription is by way of example only, and is not intended to limit theinvention so further described in such appended claims.

What is claimed is:
 1. A method for forming a solid lineal profile, themethod comprising: supplying a plurality of individual ribbons, whereineach ribbon contains a plurality of continuous fibers that aresubstantially oriented in a longitudinal direction and a resinous matrixthat contains one or more thermoplastic polymers and within which thecontinuous fibers are embedded, the continuous fibers constituting fromabout 40 wt. % to about 90 wt. % of the ribbon and the thermoplasticpolymers constituting from about 10 wt. % to about 60 wt. % of theribbon, each ribbon formed from a consolidated plurality of resinousmatrix impregnated fiber rovings; heating the ribbons to a temperatureat or above the softening temperature of the resinous matrix; afterheating of the ribbons, pulling the heated ribbons through a first dieto consolidate the ribbons together and form a laminate and through asecond die to shape the laminate; and after pulling the heating ribbonsthrough the first die and the second die, cooling the shaped laminate toform the solid profile.
 2. The method of claim 1, wherein the continuousfibers include glass fibers, carbon fibers, or a combination of glassand carbon fibers.
 3. The method of claim 1, wherein the thermoplasticpolymers include a polyolefin, polyether ketone, polyetherimide,polyarylene ketone, liquid crystal polymer, polyarylene sulfide,fluoropolymer, polyacetal, polyurethane, polycarbonate, styrenicpolymer, polyester, polyamide, or a combination thereof.
 4. The methodof claim 1, wherein the continuous fibers constitute from about 50 wt. %to about 85 wt. % of the ribbon.
 5. The method of claim 1, wherein theribbon has a void faction of about 2% or less.
 6. The method of claim 1,wherein from 10 to 30 individual ribbons are employed to form thelaminate.
 7. The method of claim 1, wherein the ribbons are heatedwithin an infrared oven.
 8. The method of claim 1, wherein the laminateis allowed to cool after exiting the first die and before entering thesecond die.
 9. The method of claim 1, wherein annealing is conductedwith a water tank that is maintained at a temperature of from about 1°C. to about 15° C.
 10. The method of claim 1, wherein a first portion ofthe ribbons has a greater tensile strength in the longitudinal directionthan a second portion of the ribbons.
 11. The method of claim 1, whereincontinuous fibers of the first portion include carbon fibers andcontinuous fibers of the second portion include glass fibers.
 12. Themethod of claim 1, wherein the profile has a void faction of about 2% orless.
 13. The method of claim 1, wherein the profile has a flexuralmodulus of about 10 Gigapascals or more and a flexural strength of fromabout 250 Megapascals or more.